在javascript中定义变量的快捷方式 [英] shortcut to existentially define variable in javascript

问题描述

为了避免破坏现有的变量，我有这样的代码

  window.x = typeof x！=undefined？ x：{} 
  

这似乎是一种非常冗长的方式来定义某些东西，但必须避免控制台错误。

我试了一下，而且它似乎工作正常。

  window.x = window.x || {} 
 可以定义这样的变量吗？ / code> 

甚至在全球范围内...



  x = this.x || {} 
  




解决方案如果你使用这个构造：

  window.x = window.x || {} 
  

并且定义了 x 有一个falsy值（零，空字符串，null，NaN，未定义，当然是false），那么该值将被一个新的空对象覆盖。如果您认为这是可以接受的，因为您确信 x 将完全未定义或已经定义为对象，那么确定，继续...

To avoid clobbering existing variables, I have code like this

window.x = typeof x != "undefined" ? x : {}

Which seems like a very long winded way to define something, but necessary to avoid console errors.

I tried this out instead, and it seems to work ok. Is it ok to define a variable like this?

window.x=window.x||{}

Or even in the global scope...

x=this.x||{}

解决方案

If you use this construct:

window.x=window.x||{}

And x is defined but has a falsy value (zero, the empty string, null, NaN, undefined, and of course false) then that value will be overwritten with a new empty object. If that is acceptable to you because you are confident that x will either be completely undefined or already defined as an object then sure, go ahead...

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